In a conventional retail store operation, customers walk about a store viewing merchandise items displayed on shelves, racks, or special display apparatus or set ups. A customer may select an item from its displayed position and place it in a shopping container such as a cart, basket or the like. Additional items may be selected and also be placed in the container by the customer. An item may also be removed from the container and placed back in its display position, or even placed in some other display position.
Eventually, the customer stops viewing merchandise and proceeds to a check out or other point-of-sale location to pay for the items selected. After payment, the customer takes the selected items outside the retail store, whether by using the same container used for merchandise selection, or by use of another type of carrying object such as a box or bag, or just by carrying the items by hand.
Various automatic methods have been devised to improve this process through application of technologies such as bar code markings and readers, or us of RFID tags. Schkolnick et al. in U.S. Pat. Nos. 6,032,127 and 5,729,697 describe an intelligent shopping cart that can automatically keep track of objects selected and placed in the cart. The objects have radio frequency tags attached. A radio frequency field from an antenna within the cart interrogates the radio frequency tags on objects with the cart. The cart has a computer to cause a periodic interrogation of all tags within the radio frequency field. A data structure within the computer's memory is then updated to include an entry for each object within the cart. The computer may also perform other useful features such as computing the total cost of all items currently in the cart and displaying this running total on a cart display. The computer may also have a credit card reader attached thereto, allowing a customer to pay the running total by swiping a credit card through the reader.
RFID tags are capable of providing considerable identification data in response to an interrogation by a tag reader, the data may be related to the object the tag is attached thereto, having been specified at the time the tag was attached. However, current RFID tag technology by itself does not provide sufficient positional accuracy to identify objects e.g. retail items by their position on a shelf in a store.
A global positioning system GPS receiver can be attached to the RFID tag to provide improved positional accuracy information. However, such GPS receivers are considerably more expensive than the attached RFID tag and although improved, still do not provide the positional accuracy needed for small retail items in a retail store.
Optical methods for tracking objects provide much higher positional accuracy. For example, Allen in UK Patent Application GB 2 247 592 A describes a rotatable reflector having a low moving mass so that a surveillance camera view can be rapidly moved in pan and tilt angles. A positional sensor on the reflector as well as relevant camera resolution provides high positional accuracy over a large range of angles.
Weinshall et al. in International Publication Number WO 02/017235 published Feb. 28, 2002, describe a rotating mirror apparatus. In this invention, the mirror may have a curved region of high magnification and additional regions of low magnification to produce an overall panoramic view.
Alternatively, two cameras of differing magnification and field of view with a flat mirror, the high magnification region may be used along with mirror angle data to produce high positional accuracy determination.
Sieber et al. in U.S. Pat. No. 5,231,483 describe an apparatus for tracking a moving object. An angular error between the camera and tracked object is processed in a digital processor to produce a video picture pleasing to human viewers.
Lee describes in U.S. Pat. No. 6,507,366 an apparatus and method for tracking an object using a camera, a zoom lens, and an automatic focus lens. The camera may be rotated about two perpendicular axes. A pan/tilt controller detects a motion vector of a tracked object and controls the camera to move in the direction of the motion vector. A zoom controller may be used to expand object search range beyond the limit of the rotational range in at least one direction.
Despite such developments, optical methods have not been widely used in retail store operations due to significant limitations such as cost, inability to track more than one object simultaneously.